Stripper mechanism



J. G. LIEBENOW ETAL STRIPPER MECHANISM Filed Sept. 28, 1955 July 22, 195

I Julius 6km Lz'eerzozx/ GZ'Zerz? I llz'eerzozx/ United States Patent STRIPPER MECHANISM Julius Gus Liebenow, Berwyn, and Gilbert I. Liebenow, Mount Prospect, 11].

' This invention relates to a stripper mechanism for a printing press that has been converted to a die-cutting apparatus. I

For purposes of illustration the features of the present invention have been shown and applied to a well known Miehle type printing press.

Difficulties in the use of converted printing presses were heretofore encountered at the point where the die-cut cardboard material is transferred from the cylinder to delivering tapeswith the aid of lifting or stripping fingers. The chief difiiculty was'that portions of the die-cut sheets were intercepted below the stripping 'or lifting fingers instead of moving over said fingers as intended. The reason for this is that typical die-cutting operations convert a solid sheet of cardboard into a series of small sections interconnected in the manner of a chain. Ordinary sheet material passing throughanunconverted printing press, consists of coherent sheets, all portions of which move over the conventional stripping fingers in a substantially identical manner. It is not so in the case of die-cut material, large portions of which tend toform a catenary, which causes difliculty mainly at the point of maximum rise of the catenary curve from the ideal, fiat position of the sheet.

Attempts have been made to cure the difficulty by interconnecting the different portions of the die-cut sheet by large numbers of so called notches or small connecting members integral with the sheet material. However, this method of solving the difiiculty is rather unsatisfactory as to efficiency and economy in the operation of the diecutting knives utilized in the press and in the die-cutting of the sheet, as it mutilates the die, produces an inferior finished product with scarred edges, increases cutting'load on the machine, necessitates additional hand labor to separate finished subjects from the die-cut sheet, and severely limits use of automatic air-hammer equipment developed for the finishing operation.

The present invention avoids the necessity of using a large number of notches in the die-cut sheets, thereby adding to the efficiency and economy of the entire machine and also facilitating the subsequent operation of separating the die-cut elements from the original sheet.

This has been achieved by arrangement of the lifting or stripping fingers relative to the machine elements cooperating therewith. In the unconverted printing press the sheet material, in process of being stripped from the cylinder, moves downwardly therefrom onto the conveyor tapes or belts which carry the material away from the cylinder. According to the invention, in the printing press converted to die-cutting the sheet material is allowed partly to move downward and partly, so far as necessary, to move a slight distance outward to the level of the conveyor tapes or belts. This is achieved by a rearrangement of operative parts without extensive or expensive changes of any major machine elements. The details will appear clearly from the description which follows.

In the drawing:

ice

Figure 1 is a plan view of a die-cut sheet which can be stripped from a cylinder according to the present invention.

Figure 2 is a front view of the sheet of Figure 1.

Figure 3 is a sectional elevation of the present stripper mechanism, also showing parts directly connected or associated therewith.

The die-cut sheet 10 is transferred from the so-called impression cylinder 11 to the conveyor tapes or belts 12, upon the release, of the sheets by the well-known grippers 13. The transfer of the sheets from the cylinder to the tapes is effected by stripper fingers 14 (only one shown) each of which has its front tip 15 slightly spaced from the surface of the cylinder 11. Each finger also has a hub section 16 at the opposite or back end of the finger and adjacent to the front end of the tapes. A plurality of stripper fingers 14 is usually provided, in a basically known manner, all of these fingers being carried on a stripper finger shaft 17 which is stationary and which is sectionally engaged by the fingers, subject however to the possibility of slightly adjusting the angular position of the fingers and distance of tips 15 from the cylinder 11.

The shaft 17 has its ends mounted in a pair of bracket members 18,. one at each end of the cylinder, and these bracket members also provide support and bearing means or pulleys 19 for the tapes or belts 12, on a shaft 20; the

finger support shaft 17 being desirably interposed between the. belt roller shaft 20 and the cylinder 11. In addition, the brackets 18also known as tape frame bracketssupport shaft and/or stub shaft means 21, 22 for a set of small gears 24. and 25, the first of which is activated by a gear 23 meshed with a large gear 27 rotating with the cylinder 11 While the gear 25 meshes with a gear 26 on shaft 20 to rotate the pulleys 19 for'the tapes 12; the intermediate gears being adapted to idle on their respective shafts or sub-shafts. In the simple embodiment shown, the members 19 serve both bearing and pulley, rotating with the shaft 20 and having the gear 26 fast thereon. This gear train assembly of course is subject to various modifications which are obvious to persons skilled in the art. The tape frame brackets 18 may also provide a new manner for the installation of so-called rider wheel bracket 28 with rider wheels 29 thereon, while suitable bolt members 30 may be installed between the two brackets in order to strengthen and stabilize the entire stripper mechanism.

In the operation of the present mechanism a cardboard sheet 10' is first secured to the cylinder 11 by the grippers 13 and rotated with the cylinder; the grippers 13 moving between the spaced apart fingers 14 and the sheet 10 moving between the finger tips 15 and the boundary of the cylinder. At a suitable point, not shown, a wellknown cutting or punching mechanism performs the diecutting operation, removing various portions 31, 32, 33, 34, 35, 36, 37, etc. from the sheet, while leaving the remaining die-cut member 38 interconnected by longitudinal notches 39 as well as transverse notches 40; additional notches 41, 42 being used to connect the section with the outer margin 43 of the die-cut sheet, so that they can still be handled as a unit until they are ready to be separated from one another by manually or automatically paring oif the various notches 40, 41, 42 and 43. The length as well as the other dimensions of the different notches has been exaggerated to some extent, in the drawing, as compared with the dimensions used in most practical operations. Likewise the dimensions of cut-out spaces 32, 34, etc. has been exaggerated. It will be understod that practically endless modifications are possible in these respects. In all cases, however, there is at least some tendency for the various sections 38 to form a catenary, as is most clearly shown in Figure 2.

When the die-cutting has been completed, the cylin- 3 cler 11 brings the die-cut sheets into the approximate position shown in Figure 3, where the grippers 13 release said sheets at the front end thereof, whereas the rider wheels 29 continue toinsure contact. of the sheet with the cylinder at the top of the latter. As the cylinder continues to rotate, the front edge or margin 43; of the sheet moves forward, substantially in the flat position shown in Figure 2. Shortly thereafter successive rows of die-cut sections 38 move forward and these, as mentioned, tend to sink into the catenary position, also shown in Figure 2. Their precise position 'is dependent mainly upon the shapes of the die-cut aside from strength of the sheet material and other operating factors. In spite of the catenary formation of inner portions of the die-cut sheet, the fingers 14, uniformly installed on their shaft 17, elfectively guide all portions of the sheet 10 onto the tapes 12 because the stripper finger tips 15 are positioned slightly below the plane of the upper receiving run of the tapes 12, as clearly visible in Figure 3; said upper run in turn being disposed in a plane adja-' cent to but below a tangent on the upper part of the cylinder 11. Heretofore stripper fingers were used which were more tangent on the cylinders and the plane of the delivering tapes was higher, which arrangement, as mentioned, led to difliculties when used with die-cut material. In the present machine both tapes 12 and fingers 14 extend slightly below plane tangent on the cylinder, and the fingers extend at least somewhat farther below the tangent plane than the tapes do. By means of this arrangement the difliculty has been fully avoided.

It should be obvious that, in the present arrangement,

' practically the entire tapes and frame brackets are used in almost the same form that they previously had. It has been necessary to provide the present sequence of the parts 11, 14, 19, as compared with the previously used sequence in a printing press wherein the cylinder 11 is followed first by tape wheel pulleys and thereafter by a stripper finger support shaft; the fingers being in- 4 stalled in steeper positions than in accordance herewith. No difiiculty results from the existence of slight gaps 44 between the present stripper finger hubs 16 and tape pulley 19. In this connection, again, the operation according to the present invention is aided by the feature that at least portions of the die-cut sheets move upwards relative to the plane of the operating run of the tapes 12.

We claim:

Apparatus for lifting and delivering die-cut sheets from a press cylinder, comprising a set of tapes; pulley means for each tape; a pair of tape frame brackets for connecting the pulley means with'the cylinder so that an upper run of each tape extends inia plane adjacent to and slightly below a line tangent to the top of the cylinder, said plane sloping downwards from the cylinder; and a set of lifting fingers secured to the tape frame brackets between the pulley means and the cylinder one in longitudinal alignment with each tape, each lifting finger having a substantially fiat top surface extending from adjacent the cylinder to adjacent the pulley means in a plane slightly below and relatively rising to the plane of the upper run of the delivery tapes, whereby die-cut sheets can be lifted and smoothly transferred from the cylinder to the tapes in spite of a tendency of inner portions thereof to saginto a catenary curve.

References Cited in the file of this patent UNITED STATES PATENTS 621,839 Miehle Mar. 28, 1899 654,248 Hager July 24, 1900 1,012,538 Fisher Dec. 19, 1911 1,339,807 Butler May 11, 1920 1,666,203 Harshberger Apr. 17, 1928 1,826,889 Koch Oct. 13, 1931 2,004,658 Gerard June 11, 1935 2,145,048 Hagen Jan. 24, 1939 2,485,020 'Staude Oct. 18, 1949 2,603,262 Urschel July 15, 1952 

